What this calculator works out
This calculator multiplies your essential monthly costs by the number of months you want covered, then subtracts what you have already saved. It returns a target figure and the gap still to close.
The maths is trivial. The two decisions that determine whether the answer is useful are what counts as essential, and how many months is right for your situation. Both are covered below.
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Before you set a target
- Work out essential costs, not total spending. Essentials are the things that would still have to be paid if your income stopped: housing, utilities, food, transport to work, insurance, minimum debt repayments and childcare.
- Exclude what you would cut. Subscriptions, holidays, meals out and discretionary shopping do not belong in an emergency figure, because in an emergency they would stop.
- Count only money you can reach quickly. Cash in an instant-access account counts. Money in investments, a pension or a fixed-term bond does not, because it may be inaccessible or worth less exactly when you need it.
- Be realistic about your income stability before choosing a number of months.
An emergency fund is not an investment. Its job is to be available at full value on a day you did not choose. Investing it risks having to sell at a loss during the same downturn that caused the job loss, which is the moment the fund exists to cover.
How this calculator works
Two steps, both exact:
Target = essential monthly costs × months of cover
Still to save = target − amount already savedIf you already hold more than the target, the gap is shown as zero rather than a negative figure. The calculator does not apply interest, because a cash buffer is held for availability rather than growth, and the amounts involved over the period concerned make the difference immaterial.
Worked example: £1,800 of essential costs
Using the default figures — essential monthly costs of £1,800, a target of six months' cover, and £3,000 already saved:
- Target: £1,800 × 6 = £10,800
- Still to save: £10,800 − £3,000 = £7,800
£7,800 is a daunting number, and seeing it whole is where most people give up. It is more useful reframed: at £200 a month it takes about three years and three months, and the first £1,800 — one month of cover, reached in nine months — removes the majority of the risk of a single unexpected bill turning into debt. Partial progress is genuinely valuable here in a way it is not for most financial goals.
Common mistakes
- Using total spending instead of essential spending. This inflates the target, often by a third or more, and makes it feel unreachable.
- Counting money that is not accessible. A fund you cannot draw on within a few days is not an emergency fund.
- Investing the fund to make it work harder. The one time you need it is disproportionately likely to be a time when markets are down.
- Waiting until debts are cleared before starting. A small buffer, often suggested at around £1,000, usually comes first, because without it the next unexpected cost goes straight back onto the credit card.
- Leaving it in a current account earning nothing. An instant-access savings account keeps the money available while paying interest.
Frequently asked questions
How many months should I aim for?
Three to six months of essential costs is the usual guidance. Lean towards three if you have secure employment, a second income in the household and few dependants. Lean towards six or more if you are self-employed, on a variable or commission-based income, the sole earner, or working in an industry where finding a comparable role takes time.
Should I build this before paying off debt?
Usually a small starter buffer comes first, then high-interest debt, then the full fund. Clearing a credit card charging over 20% is worth more than holding cash earning far less, but attacking debt with no buffer at all tends to fail: the next car repair goes back on the card and the progress is undone.
Where should I keep it?
An instant-access savings account, separate from your current account so it is not spent by accident. Check whether your balance stays within the Financial Services Compensation Scheme limit at any single banking group. A cash ISA can also work if you have allowance available.
Does the fund need to keep pace with inflation?
It needs to keep pace with your costs, which is a slightly different question. Review the target annually, and whenever your rent, mortgage or childcare changes. If essential costs rise 8%, the target rises 8% too.
Is what I enter here stored?
No. Your costs and savings balance are processed entirely in your browser and are never transmitted or retained.
Related tools
References
- MoneyHelper — guidance on emergency savings, how much to hold and where to keep it
- Financial Conduct Authority — regulation of savings providers and the compensation limits that apply
Sources are checked at publication and can change — how I choose and check references.